you only need 1 gpu
bind your gpu to the first screen then use "io.write" to write "Computer Lab"
Then bind it to the second screen.
If you want to write a message to the first screen just bind the gpu to the first screen again.
If you need to use 2 gpus then do the following.
component = require("component")
component.setPrimary("gpu","your gpu address")
then just use io.write()